Drill bit



0. DUDA May 17, 1932.

DRILL BIT.

Filed April 23, 1928 abtoz "4241 'atented may 17, 1932 OSWALD DUDA,

PANY, 01E HOUSTON, TEXAS or SOUTH HOUSTON, TEXAS, ass enoa To Burn) ROLLER arr com- A CORPORATION OF TEXAS DRILL BIT Application filed April 23,

embodying cutting blades strongly supported in a new and improved manner against move ment 1n the head when the drill is rotated in either direction about its longitudinal axis. 1

Another object is to provide new and imroved cutting blades for drill bits. The fish tail bit now commonly used, so-called because of the shape of its cutting blades, ordinarily 'cuts a hole triangular in crosssection and becomes locked therein. Aside fromthe damage and delay thereby caused, it is necessary to thereafter ream the hole to the desired circular cross-section. Various bits have been suggested to obviate the fore going objections to the bit commonly used,

but none of these, so far as I know, have The new and improved blades provided by this invention cut a hole uniformly circular in cross-section, thus eliminating all danger of the bit becoming I looked in the hole and the necessity of reaming the hole after drilling it.

One embodiment of the invention is illustrated in the accompanying drawings wherein Fig. 1 is a side elevation of the'bit; Fig. 2, a side elevation at a right angle to Fig. 1; and Fig. 3, a bottom plan view.

The head of the bit 1 has in its bottom a pair of transverse slots 1a and 1b the inner side walls of'said slots lying infsubstantially the same plane, preferably that of the transverse axis of the head. Depending projections 10 and 101 on said head are disposed immediately adjacent slots 1a and 1?), respectively, the inner flat walls of said projections forming continuations of the inner side walls of said slots. p

The upper ends of cutting blades 2 and 3 are shaped to fit in slots 1a and '16, so that the inner portions of said blades overlap each other.

communicating with each other and substantiallyfrom the longitudinal axis 1928. Serial No. 272,080.

The blades may be held in the head by screws 4 and 5 or the like.

Inward movement of the blades is positively prevented by the engagement of the outer portions 2a and 3a and the head.

WVhen the bit is rotated in drilling, the blades are supported by the side walls of the slots 1a and 1b, the depending projections 10 and 1d, and by each other because of their overlapped inner portions. When the bit is rotated in the opposite direction, the blades are supported by the outer sides 16 and 1h of the head fitting in the grooves 26 and 3b.

The blades of bits now in common use have narrow outer side edges. The outer side edge of one blade becomes caught on the vertical wall of the hole, and the bit swings on said edge as an axis until the outer side edge of the other blade becomes caught, whereupon the bit swings on the latter-edge as an axis. This actlon produces a hole triangular in crosssection. Ultimately the bit becomes locked in the hole thereby causing both damage and delay. d

The outer sides 2a and 3a of the blades provided by this invention present a broadsurface tothe vertical wall of the hole and are designed to cut the hole circular in crosssection. In the preferred embodiment, the

sides 2a and 311 have vertical cutting teeth 20 and 30 thereon. i

It is to be understood that various embodiments of this invention, other than that disclosed in the accompanying drawing, are within thev scope of the following claims.

I claim 1. A drill blade having an outer side portion ext-ending at substantially a right angle to its body portion, said side portion having spaced, longitudinally extending cutting teeth, and an internal longitudinal groove for the reception of the side of a bit head.

2. A drill bit head having a pair of substantially parallel slots in the bottom thereof extend- E ing of the head to opposite sides thereof, and depending projections adjacent said slots, and a pair of blades in said slots, on said r I j projections, and with their 'inner ends over lapped. 1

3, A drill bit head having a pair of substantially parallel slots in the bottom thereof communicating With each other and extending substantially from the longitudinal axis of the head to opposite sides thereof, and depending projections adjacent said slots, and a pair of blades in said slots, said blades having overlapped inner ends, and outer portions extending substantially at right angles to their body portions and grooved for the reception of said projections.

4. A drill bit head having a pair of substantially parallel slots in the bottom thereof extending substantially from the longitudinal axis of the head to opposite sides thereof, and depending projections adjacent said slots, and a pair of blades in said slots, said blades having overlapped inner ends, and outer portions extending substantially at right angles to their body portions, internally grooved for the reception of said projections, and having external, spaced, longitudinally extending teeth.

5. A drill bit head having a pair of substantially parallel slots in its bottom and ex tending substantially from its longitudinal axis to its opposite sides, and depending projections adjacent said slots, and a pair of blades fitting snugly in said slots, on said projections, and with their inner ends over lapped.

6. A drill bit head having a pair of substantially parallel slots in its bottom and extending substantially from its longitudinal axis to its opposite sides, and depending projections adjacent said slots, and a pair of blades fitting snuglyin said slots, said blades having overlapped inner ends, and outer portions extending substantially at right angles totheir body portions and grooved for the reception of said projections. r

In testimony whereof, I hereunto aflix my signature.

OSWALD DUDA.

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